[Relationship between methicillin resistant Staphylococcus aureus from inpatients and parenteral antibiotics]

We examined the relationship between clinical isolates from inpatients, mainly methicillin resistance Staphylococcus aureus (MRSA), and usage of parenteral antibiotics in Yamagata University Hospital and comparison of the relationship of the previous decade and the present. The first period was from 1988 to 1990 in a row, and the second period was from 1998 to 2000 in a row. In the first period, third generation cephems were used much and usage of antibiotics was shifted from latamoxef to flomoxef. Isolations of MRSA were decreased. In the second period, the third generation cephems decreased, cefazolin and the forth generation cephems increased. And also decrease in usage of penicillins was observed. Isolations of MRSA were increased. For further examination of these relation, we studied by statistical analysis the number of MRSA patients and usage of antibiotics per month in the second period. MRSA patients showed positive correlation with cephems and carbapenems, negative correlation with penicillins. In major antibiotics MRSA patients showed positive correlation with cefazolin, negative correlation with piperacillin. In multiple linear regression analysis, MRSA patients calculated multiple regression model including cefazolin. In conclusion, it was suggested that cefazolin related with MRSA. It has been estimated that cefazolin were administered before the appearance of MRSA. It is a possibility that cefazolin related with the appearance or fixation of MRSA.